Microfacies and paleoenvironment of Aaliji Formation in selected wells in from Kirkuk and Jambur fields northeastern Iraq

Abstract

The Aaliji Formation was studied in selected wells (K_411, K_243 and Ja_40) in northeastern Iraq. From the petrographic study, it was found that most of the skeletal grains consist of planktonic foraminifera such as Morozovella sp, Acarinina sp, Subbotina sp, Igorina sp and Globorotalia sp and very rare of benthonic foraminifera presence like (Nodoaria sp and Bulimina sp) in addition to some ostrocods. Non-skeletal grains are represented by quartz and phosphate granules embedded in the groundmass is mainly composed from brown to blue micrite. The formation is affected by a number of diagenesis processes such as compaction, cementation, dissolution, recrystallization and Authigenic minerals such as pyrite and glauconite are present. According to the microfacies analysis, four main microfacies diagnosed: lime mudstone, lime wackestone and lime packstone, these facies were divided into seven submicrofacies: Bioclast lime Mudstone, Planktonic Foraminiferal Lime Mudstone, Benthonic Foraminiferal lime Wackstone, Globular Planktonic Foraminiferal lim Wackestone, Keeled Planktonic Foraminiferal lime Wackestone, Planktonic Foraminifera lime Packstone, Bioclast lime Packstone. From the study of the microfacies and the petrography, it was found that Aaliji Formation was deposited within two environmental Zones (Deep Sea and Deep Shelf) the present study shows that a large part of the facies have been deposited within the first and second deep zones. The lower boundary of the formation represents an unconformable surface with the Shiranish Formation, also the upper boundary unconformable with Jaddala Formation.